1. Field of the Invention
The present invention relates to a diaphragm device for light source light adjustment ideally disposed in the vicinity of a light source of a projecting apparatus, a projector, or the like.
2. Description of the Related Art
There has been known a projecting apparatus used for lighting on a stage or at a studio that has a diaphragm device disposed near a light source to restrict the projecting range or projecting configuration of light emitted from a light source (refer to Japanese Unexamined Patent Application Publication No. 7-99002). It is known that liquid crystal projectors and other various types of projectors have diaphragm devices disposed near light sources to temporarily change the quantity of lighting according to the brightness of projection room or to change projection images. Especially in the case of a liquid crystal projector, disposing such a diaphragm device is known to make it possible to restrain deterioration of a liquid crystal panel (refer to Japanese Unexamined Patent Application Publication No. 2001-174910).
In a projecting apparatus or a projector, the area near a light source becomes hot due to visible light rays or infrared rays emitted from the light source. Therefore, heat radiating measures or heat resistance measures have always been major considerations in developing projecting apparatuses or projectors. The diaphragm device disclosed in the Japanese Unexamined Patent Application Publication No. 2001-174910 is provided as heat measures for a liquid crystal panel.
However, diaphragm devices provided for such purposes may fail to function if they are overheated by intense light of light sources. To prevent such a problem, therefore, a protective means, such as a shutter, having a special construction is provided between a diaphragm device and a light source to primarily block infrared rays from a light source, as described in the Japanese Unexamined Patent Application Publication No. 7-99002. Disposing such a special protective means between the diaphragm device and the light source makes it possible to protect the diaphragm device from overheating.
Projecting apparatuses are recently being used for a variety of displays used indoors and outdoors, and with its accelerating demand, the number of types thereof is increasing. In addition, there has been growing needs for inexpensive, smaller types. With the advent of data projectors, such as liquid crystal projectors, the projectors are being frequently carried around by sales persons to perform presentation of products. This has led to the need for smaller, inexpensive projecting apparatuses featuring good portability.
Thus, an attempt to respond to the need for lower cost and compactness by adding protective means that have complicated constructions is not a successful solution. Hence, there has been a demand for developing ideal measures for protecting diaphragm devices from overheating without the need for providing such special protecting means.